Our objective is to understand the function and mechanism of action of the first major secreted protein of the ovine conceptus, ovine trophoblast protein-1 (oTP-1) and the immunologically related bovine protein bTP-1. These proteins have been implicated in the process of maternal recognition of pregnancy in the ewe and cow. oTP-1 is produced between D 13 and 21 of pregnancy and maximally in the D 15-17 period. It appears to interact with the epithelial cells of the maternal uterus. We intend to improve the efficiency of oTP-1 purification by high performance chromatographic techniques and purify the immunologically cross-reacting bovine TP-1 for the first time. The relationships between the isoforms of the two proteins will be investigated by peptide mapping and by using monoclonal antibodies. We shall determine whether total conceptus secretory proteins, from which oTP-1 has been removed by immunoadsorption, can extend the lifespan of the corpus luteum when they are infused into the uterus of nonpregnant recipients. We shall also study whether the endometrial proteins which are induced by oTP-1 are produced during pregnancy. In the second part of the project, the main objective is to use recombinant DNA techniques for studying the structure, biosynthesis and function of oTP-1 and the related bTP-1 of the cow. We shall attempt to isolate "full length" cDNA's to oTP-1 and bTP-1 from cDNA Libraries in the plasmid vector pUC-18 (already established). The nucleotide sequences of these cDNA's will be determined and primary amino acid sequences inferred. These sequences will be compared for homology with other known proteins and polypeptide hormones. The kinds of mRNA and their quantities will be evaluated in conceptuses during the period of maternal recognition of pregnancy. A final objective is to produce oTP-1 in quantity in a bacterial or mammalian cell system with the view to obviating the need for culturing large numbers of conceptuses. Longer term goals will be to determine whether conceptuses of other species produce oTP-1-like proteins and to introduce the full length genes for oTP-1 into fertilized eggs, with the view to producing transgenic animals which may have increased fertility.